1. Technical Field
Novel photoresist monomers, polymers thereof, and photoresist compositions comprising the polymers are disclosed. More specifically, novel dipropargyl acetamide photoresist monomers, polymers and compositions having excellent post-exposure delay (PED) stability in a deep ultraviolet region are disclosed.
2. Description of the Background Art
In general, a useful photoresist (hereinafter, abbreviated as xe2x80x9cPRxe2x80x9d) has a variety of desired characteristics, such as high light transmissibility at the wavelength of 193 nm, excellent etching resistance, heat resistance and adhesiveness. In addition, a photoresist should be easily developable in a commercially readily available developing solution, such as 2.38 wt % aqueous tetramethylammonium hydroxide (TMAH) solution. However, it is very difficult to synthesize a photoresist polymer that satisfies all of these criteria.
To solve some of the problems described above, much research has been done on a resin having the high transparency at the wavelength of 193 nm and dry etching resistance similar to a novolac resin used in an i-line. For example, IBM has developed the following methacrylate copolymer resin: 
wherein, R1, R2 and R3 are independently H or CH3.
In the above resin, the ratio of xe2x80x9cxxe2x80x9d must be increased in order to improve the dry etching resistance. However, if the amount of xe2x80x9cxxe2x80x9d is increased, hydrophilicity of the resin itself is reduced, therefore a thin pattern may collapse. In order to overcome such a disadvantage, hydrophilic monomers such as a methacrylic acid are copolymerized. However, in this case, a photoresist top loss may occur during developing, and thus a special developing solution such as a diluted solution or a solution containing isopropylalcohol must be employed, instead of the currently used developing solution. In addition, if the resin does not contain a predetermined degree of the alicyclic compounds, it cannot satisfy the etching resistance criteria. In addition, the polymer is very sensitive to environment, and thus hard to obtain sufficient post exposure delay (PED) stability.
In general, when there is delay between exposure of the photoresist to light and development of the exposed photoresist, acids that are generated on the exposed area are neutralized by amine compounds which may be present in the production atmosphere. Since the pattern formation depends on acids that are generated by the exposure, neutralization of acids by atmospheric amine compounds reduce, prevent or alter a pattern formation, e.g., a T-topping phenomenon may occur where the top portion of the pattern forms an undesirable T-shape.
A photoresist monomers having an enhanced PED stability are disclosed.
PR polymers using the PR monomers described above and a process for preparing the same are also disclosed.
Photoresist compositions using the PR polymers described above are also disclosed.
A semiconductor device produced by using the above described PR composition is also disclosed.